The present invention relates to a semiconductor device and a manufacturing method for the same, and can be applied to the manufacture of, for example, a semiconductor device including a trench-type MOSFET.
As an example of a field-effect transistor in which a current is made to flow between the main surface side and reverse side of a semiconductor substrate, a trench-gate type (vertical) MOSFET (metal oxide semiconductor field-effect transistor) is known which includes gate electrodes formed in ditches which are formed in an upper surface portion of a semiconductor layer formed over the main surface of the semiconductor substrate.
In Japanese Unexamined Patent Application Publication No. 2010-258252 (patent document 1), a vertical MOSFET is disclosed which includes a source region formed in an upper surface portion of a semiconductor layer formed over a semiconductor substrate, a drain region formed on the reverse side of the semiconductor substrate, and gate electrodes formed in ditches which are formed in an upper surface portion of the semiconductor layer. In the vertical MOSFET, portions of each gate electrode are extended with a narrow width toward the drain region side.